llvmPackages_16.lld: backport table-base patch

From 93adcb770b99351b18553089c164fe3ef2119699 Mon Sep 17 00:00:00 2001

From: Sam Clegg <sbc@chromium.org>

Date: Fri, 25 Aug 2023 13:56:16 -0700

Subject: [PATCH] [lld][WebAssembly] Add `--table-base` setting

This is similar to `--global-base` but determines where to place the

table segments rather than that data segments.

See https://github.com/emscripten-core/emscripten/issues/20097

Differential Revision: https://reviews.llvm.org/D158892

---

 test/wasm/table-base.s | 72 ++++++++++++++++++++++++++++++++++++++

 wasm/Driver.cpp        | 19 ++++++++--

 wasm/Options.td        |  5 ++-

 wasm/Writer.cpp        |  8 -----

 4 files changed, 93 insertions(+), 11 deletions(-)

 create mode 100644 test/wasm/table-base.s

diff --git a/test/wasm/table-base.s b/test/wasm/table-base.s

new file mode 100644

index 000000000000000..56fff414fd31d96

--- /dev/null

+++ b/test/wasm/table-base.s

@@ -0,0 +1,72 @@

+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %s -o %t.o

+

+# RUN: wasm-ld --export=__table_base -o %t.wasm %t.o

+# RUN: obj2yaml %t.wasm | FileCheck %s  -check-prefix=CHECK-DEFAULT

+

+# RUN: wasm-ld --table-base=100 --export=__table_base -o %t.wasm %t.o

+# RUN: obj2yaml %t.wasm | FileCheck %s  -check-prefix=CHECK-100

+

+.globl _start

+_start:

+  .functype _start () -> ()

+  i32.const _start

+  drop

+  end_function

+

+# CHECK-DEFAULT:       - Type:            TABLE

+# CHECK-DEFAULT-NEXT:    Tables:

+# CHECK-DEFAULT-NEXT:      - Index:           0

+# CHECK-DEFAULT-NEXT:        ElemType:        FUNCREF

+# CHECK-DEFAULT-NEXT:        Limits:

+# CHECK-DEFAULT-NEXT:          Flags:           [ HAS_MAX ]

+# CHECK-DEFAULT-NEXT:          Minimum:         0x2

+# CHECK-DEFAULT-NEXT:          Maximum:         0x2

+

+# CHECK-DEFAULT:       - Type:            GLOBAL

+# CHECK-DEFAULT-NEXT:    Globals:

+# CHECK-DEFAULT-NEXT:      - Index:           0

+# CHECK-DEFAULT-NEXT:        Type:            I32

+# CHECK-DEFAULT-NEXT:        Mutable:         true

+# CHECK-DEFAULT-NEXT:        InitExpr:

+# CHECK-DEFAULT-NEXT:          Opcode:          I32_CONST

+# CHECK-DEFAULT-NEXT:          Value:           66560

+# CHECK-DEFAULT-NEXT:      - Index:           1

+# CHECK-DEFAULT-NEXT:        Type:            I32

+# CHECK-DEFAULT-NEXT:        Mutable:         false

+# CHECK-DEFAULT-NEXT:        InitExpr:

+# CHECK-DEFAULT-NEXT:          Opcode:          I32_CONST

+# CHECK-DEFAULT-NEXT:          Value:           1

+

+# CHECK-DEFAULT:       - Type:            EXPORT

+# CHECK-DEFAULT:           - Name:            __table_base

+# CHECK-DEFAULT-NEXT:        Kind:            GLOBAL

+# CHECK-DEFAULT-NEXT:        Index:           1

+

+# CHECK-100:       - Type:            TABLE

+# CHECK-100-NEXT:    Tables:

+# CHECK-100-NEXT:      - Index:           0

+# CHECK-100-NEXT:        ElemType:        FUNCREF

+# CHECK-100-NEXT:        Limits:

+# CHECK-100-NEXT:          Flags:           [ HAS_MAX ]

+# CHECK-100-NEXT:          Minimum:         0x65

+# CHECK-100-NEXT:          Maximum:         0x65

+

+# CHECK-100:       - Type:            GLOBAL

+# CHECK-100-NEXT:    Globals:

+# CHECK-100-NEXT:      - Index:           0

+# CHECK-100-NEXT:        Type:            I32

+# CHECK-100-NEXT:        Mutable:         true

+# CHECK-100-NEXT:        InitExpr:

+# CHECK-100-NEXT:          Opcode:          I32_CONST

+# CHECK-100-NEXT:          Value:           66560

+# CHECK-100-NEXT:      - Index:           1

+# CHECK-100-NEXT:        Type:            I32

+# CHECK-100-NEXT:        Mutable:         false

+# CHECK-100-NEXT:        InitExpr:

+# CHECK-100-NEXT:          Opcode:          I32_CONST

+# CHECK-100-NEXT:          Value:           100

+

+# CHECK-100:       - Type:            EXPORT

+# CHECK-100:           - Name:            __table_base

+# CHECK-100-NEXT:        Kind:            GLOBAL

+# CHECK-100-NEXT:        Index:           1

diff --git a/wasm/Driver.cpp b/wasm/Driver.cpp

index 84304881f5ca34e..c2f5f0185781f36 100644

--- a/wasm/Driver.cpp

+++ b/wasm/Driver.cpp

@@ -502,6 +502,7 @@ static void readConfigs(opt::InputArgList &args) {

   config->initialMemory = args::getInteger(args, OPT_initial_memory, 0);

   config->globalBase = args::getInteger(args, OPT_global_base, 0);

+  config->tableBase = args::getInteger(args, OPT_table_base, 0);

   config->maxMemory = args::getInteger(args, OPT_max_memory, 0);

   config->zStackSize =

       args::getZOptionValue(args, OPT_z, "stack-size", WasmPageSize);

@@ -573,6 +574,17 @@ static void setConfigs() {

     if (config->exportTable)

       error("-shared/-pie is incompatible with --export-table");

     config->importTable = true;

+  } else {

+    // Default table base.  Defaults to 1, reserving 0 for the NULL function

+    // pointer.

+    if (!config->tableBase)

+      config->tableBase = 1;

+    // The default offset for static/global data, for when --global-base is

+    // not specified on the command line.  The precise value of 1024 is

+    // somewhat arbitrary, and pre-dates wasm-ld (Its the value that

+    // emscripten used prior to wasm-ld).

+    if (!config->globalBase && !config->relocatable && !config->stackFirst)

+      config->globalBase = 1024;

   }

   if (config->relocatable) {

@@ -666,8 +678,11 @@ static void checkOptions(opt::InputArgList &args) {

     warn("-Bsymbolic is only meaningful when combined with -shared");

   }

-  if (config->globalBase && config->isPic) {

-    error("--global-base may not be used with -shared/-pie");

+  if (config->isPic) {

+    if (config->globalBase)

+      error("--global-base may not be used with -shared/-pie");

+    if (config->tableBase)

+      error("--table-base may not be used with -shared/-pie");

   }

 }

diff --git a/wasm/Options.td b/wasm/Options.td

index 50417d2928e0a34..bb764396bf4df14 100644

--- a/wasm/Options.td

+++ b/wasm/Options.td

@@ -191,7 +191,7 @@ def growable_table: FF<"growable-table">,

   HelpText<"Remove maximum size from function table, allowing table to grow">;

 def global_base: JJ<"global-base=">,

-  HelpText<"Where to start to place global data">;

+  HelpText<"Memory offset at which to place global data (Defaults to 1024)">;

 def import_memory: FF<"import-memory">,

   HelpText<"Import the module's memory from the default module of \"env\" with the name \"memory\".">;

@@ -224,6 +224,9 @@ def no_entry: FF<"no-entry">,

 def stack_first: FF<"stack-first">,

   HelpText<"Place stack at start of linear memory rather than after data">;

+def table_base: JJ<"table-base=">,

+  HelpText<"Table offset at which to place address taken functions (Defaults to 1)">;

+

 defm whole_archive: B<"whole-archive",

     "Force load of all members in a static library",

     "Do not force load of all members in a static library (default)">;

diff --git a/wasm/Writer.cpp b/wasm/Writer.cpp

index f25d358dc5bae6f..0576bf2907e49c4 100644

--- a/wasm/Writer.cpp

+++ b/wasm/Writer.cpp

@@ -358,13 +358,6 @@ void Writer::layoutMemory() {

       memoryPtr = config->globalBase;

     }

   } else {

-    if (!config->globalBase && !config->relocatable && !config->isPic) {

-      // The default offset for static/global data, for when --global-base is

-      // not specified on the command line.  The precise value of 1024 is

-      // somewhat arbitrary, and pre-dates wasm-ld (Its the value that

-      // emscripten used prior to wasm-ld).

-      config->globalBase = 1024;

-    }

     memoryPtr = config->globalBase;

   }

@@ -1685,7 +1678,6 @@ void Writer::run() {

   // For PIC code the table base is assigned dynamically by the loader.

   // For non-PIC, we start at 1 so that accessing table index 0 always traps.

   if (!config->isPic) {

-    config->tableBase = 1;

     if (WasmSym::definedTableBase)

       WasmSym::definedTableBase->setVA(config->tableBase);

     if (WasmSym::definedTableBase32)

  patches = [

    ./gnu-install-dirs.patch

    ./add-table-base.patch

  ];

  nativeBuildInputs = [ cmake ninja ];